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Apr 1, 2012 (Vol. 32, No. 7)

Improving Cell Culture Optimization

  • SUB Technology

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    Biogen Idec utilizes single-use bioreactor equipment in many of its cell culture optimization activities. [Thermo Fisher Scientific]

    Thomas Ryll, Ph.D., senior director, cell culture development, Biogen Idec, discussed Biogen Idec’s experience with single-use bioreactors (SUB) at the meeting.

    SUB technology has advanced significantly in the last decade with many different formats now available. “We settled on a more classical design of a stirred tank based disposable reactor system,” he explained.

    “A question we addressed early on was whether or not a disposable reactor system would offer sufficient mixing and mass transfer to support an intensive fed-batch culture. What I mean with intensive fed-batch culture is a culture that features high cell mass (maybe 20–40 million cells/mL) and thus requires a lot of oxygen delivery.”

    Mass transfer and mixing studies conducted were positive, demonstrated equivalent blending times compared to control reactor systems, and could deliver sufficient mass transfer. “We showed that 250 L and 1,000 L SUB reactors were able to grow high cell mass and could reach high titers in the 8 g/L range,” said Dr. Ryll.

    “Not every system may be able to deliver such mass transfer, and the user may want to conduct mass transfer studies and may need to tailor the system selected to the purpose in mind,” he cautioned.

    A few years ago Biogen Idec also began exploring technologies for online data acquisition to better monitor and understand culture behavior. These included automated sampling and inline metabolite analysis, automated oxygen uptake rate determination, culture capacitance, and NIR and Raman spectroscopy.

    Raman spectroscopy was judged to have the most potential and maturity to be developed into a real-time monitoring tool in a manufacturing environment. “We’ve been able to build models that can predict metabolite levels and cell mass online, and the idea is that this adds to our tool box in terms of culture understanding and perhaps will enable us to reduce and hopefully eliminate needs for culture sampling in the future,” said Dr. Ryll.

  • CD Supplements Can Lower Costs

    “Much of the focus over the past 10 years centered on increasing the duration and cell density achieved in cell culture processes. The target is to increase the integral viable cell number (IVC)­—or, as it’s sometimes referred to, the cumulative cell hours (CCH)—in order to increase and maintain the productive cell population,” said Samuel Denby, Ph.D., applications and scientific manager, BD Biosciences.

    Advanced CD-defined media can boost productivity, said Dr. Denby. “In developing next-generation CD supplements, BD has identified cellular ‘activators’ that can increase specific productivity. The result of this process is to make each cell more productive, rather than just growing an ever increasing number of cells.”

    “In comparing the cost of CD supplements versus peptones, we considered the process as a whole,” said Dr. Denby, “and looked at a number of qualitative benefits, including a lowered batch failure rate (through consistency of raw materials and upstream process output), more efficient facility usage (since upstream titers should be more predictable), and increased re-use of purification equipment before fouling. When looked at through a lens of total cost in use and time to market, CD supplements can provide significant benefits.” BD’s analysis revealed manufacturing cost savings up to 21%.

  • Regeneron’s Speed-to-Clinic Process

    “Our expression technologies are quite unlike any company out there,” said Kevin Bailey, Ph.D., vp preclinical manufacturing and process development, Regeneron Pharmaceuticals. “Our speed-to-clinic cell-line technology uses a single gene copy, heavy chain and light chain, in a targeted integration locus.”

    Regeneron is able to quickly generate CHO stables “such that when we choose our final antibody we actually have our cell line for early-stage clinical manufacturing. We can get in excess of 2 g/L with this technology, which for us is more than clinically enabling. It allows us to move our programs into tox production and clinical production very quickly. Our INDs, like everyone’s, are gated by production of materials for toxicology studies,” Dr. Bailey said.

    While early-stage clinical work proceeds, Regeneron works on a second-generation cell line using a more conventional approach. “We don’t use a targeted locus integration for high copy cell lines but do use a repressible (inducible) cell-line approach. This allows us to isolate lines and bank them in the absence of selection pressure. We have a small molecule repressor present during that stage. For manufacturing we remove the repressor and get full gene activation and very high titers.”

    Adopting a quality by design approach has been useful according to Dr. Bailey. “It guides our efforts to ensure we understand all critical quality attributes and meet necessary comparability requirements for our late-stage cell line and process.”

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